Aim of study: Barrett's esophagus is a disorder associated with reflux and an increased risk of esophageal cancer. We previously showed (Gastroenterology 1997; 113:1449-1456) an increased prevalence of symptoms of gastroesophageal reflux in first degree relatives of patients with Barrett's esophagus. The aim of the present study is to find whether first degree relatives of patients with Barrett's esophagus have an increased prevalence of this disorder compared to controls with reflux symptoms and no family history of Barrett's esophagus. Completed studies: So far, 117 probands with Barrett's esophagus have been invited to participate, 229 relatives were mailed information, and 100 relatives have returned our questionnaire. 35 of these had reflux symptoms, and 20 of these have completed the study with endoscopic examination (GCRC). Another 15 are due to come for study in the next few weeks. More probands and relatives are being recruited from the large Mayo data base and active practice of the investigators. A total of 29 matched controls have completed study concurrently (controls are studied by the investigators in a different endoscopic unit).